YSI Pro1020 - Manual (Page 9)

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EXITING THE SYSTEM SETUP MENU
To exit the System Setup menu, press the down arrow key until the ESC
- Exit box is highlighted, then press enter to return to the Run screen.
Figure 7, page 1 of System Setup menu. DO Local% is enabled.
DO LOCAL%
DO Local% can be enabled or disabled by using the up or down arrow
keys to highlight it and then pressing enter . An ‘X’ in the box next to
DO Local% indicates it is enabled, figure 7.
When DO Local% is enabled, DO% values will be expressed as %L on
the Run screen.
DO Local% allows for localized % saturation measurements, but does
not affect the mg/L readings. When enabled, the DO%L calibration
value is always 100% regardless of the altitude or barometric
pressure of the location. This deviates from YSI’s traditional method of
expressing DO% saturation where the % calibration value decreases
with a decrease in barometric pressure, i.e. an increase in altitude (See
appendix A). To determine the % calibration value when DO Local% is
disabled, divide the local, true barometric pressure in mmHg by 760
and then multiply by 100.
Example: 750/760 = 0.9868 x 100 = 98.68% calibration value when
DO Local is disabled.
When DO Local% is enabled, the Pro1020 corrects for barometric
pressure for each DO measurement instead of during calibration.
Example:
Instrument #1 with DO Local% enabled:
At 737 mmHg barometric pressure, roughly 841 ft above sea level, the
instrument would calibrate to 100%.
When taking measurements at the same location (737 mmHg) in a 20°C
fresh water sample that is completely air-saturated, the instrument
would read:
DO %L value = 100%
DO mg/L value = 8.81 mg/L (9.09
1 x .9697 2 )
Instrument #2 DO Local% disabled:
At 737 mmHg barometric pressure, roughly 841 ft above sea level, the
instrument would calibrate to 737/760 x 100% = 96.97%
When taking measurements at the same location (737 mmHg) in a 20°C
fresh water sample that is completely air-saturated, the instrument
would read:
DO% value = 96.97%
DO mg/L value = 8.81 mg/L (9.09
1 x .9697 2 )
Hence, the mg/L readings are unaffected by DO Local%.
1.) Value from oxygen solubility table (Appendix B).
2.) 737/760 x 100%, correction for barometric pressure.
LAST DIGIT SUPPRESSION (LDS)
Last Digit Suppression (LDS) can be enabled or disabled by using
the up or down arrow keys to highlight it and pressing enter . An
‘X’ in the box next to LDS indicates it is enabled. LDS rounds the DO
value to the nearest tenth; i.e. 8.25 mg/L becomes 8.3 mg/L. LDS is
automatically disabled during calibrations.
QUICK DO CALIBRATION (QUICK DO CAL)
Quick DO Cal can be enabled or disabled by using the up or down
arrow keys to highlight Quick DO Cal and pressing enter. An ‘X’ in the
box next to Quick DO Cal indicates it is enabled.